We shipped a REST API in WordPress 4.7, and the API is going to continue to be a focus of the project going forward. The great thing about that is that it allows building entirely new interfaces without touching any backend code in WordPress. As an example, we built a liveblogging app[0] (warning: unoptimised React app not meant for production) entirely using the API that provided a new interface customised just for liveblogging. This connects to any site[1] and any theme.

WordPress has always had an advantage with the degree of customisation that's allowed, and my hope is that we'll see even more work towards better experiences with a shorter build-test-release cycle now. But, plugins aren't the only solution.

In WordPress itself, the big focusses for the next release (4.8) are the REST API, the Customiser (frontend live customisation), and the Editor. I think we'll see plenty of movement in this area.

(I'm one of the leads on the API, a committer to WordPress, and also work for an enterprise WP agency.)

[0]: http://app.aweekofrest.hm/ [1]: https://aweekofrest.hm/liveblog/